Ti^(4+)固溶堇青石的制备、结构和红外辐射性能的研究

Preparation, structure and infrared radiation properties of Ti^(4+)-substituted cordierite system

采用固相反应法制备了名义组成为Mg2(1-x)Ti2xAl4(1+x)Si(5-4x)O18(x=0、0.1)的堇青石体系红外辐射材料, 采用XRD、IR、29Si MAS NMR等方法研究了材料的结构,并考查了 Ti4+固溶及合成温度对材料红外辐射性能的影响。研究结果表明样品中形成以α 堇青石为主体的晶体结构。Ti4+ 的固溶使 T1(与[MgO6]八面体一起在六元环之间起连接作用的四面体)和T2(组成六元环结构的四面体)四面体上 Al、Si分布的有序度提高, 引起α 堇青石晶格畸变,增强了晶格振动的非简谐效应,从而提高了样品的红外辐射性能。合成温度的提高有利于 Ti4+ 固溶堇青石的充分形成和红外辐射性能的改善。合成温度为1420℃时,样品的法向全波段的辐射率达到 0.89,在 8~14μm波段范围内的辐射率达到0.90~0.94。

A novel infrared radiation material of Ti4+-substituted cordierite system was developed using the conventional solid state reaction method. The structure of the material was investigated by XRD, IR and 29Si MAS NMR. The effects of Ti4+-substitution and calcining temperature on the infrared radiation properties were examined. The results confirm the formation of crcordierite as the main crystal phase for the material. The substi-tution of Ti4+ in crcordierite structure promoted the ordering of the distribution of Al and Si atoms in the T1 (tetrahedra acting as connection between hexatomic rings together with [MgO6] octahedron ) and T2 (tetrahe-dra forming the hexatomic ring structure) tetrahedral sites and led to the lattice deformation of crcordierite structure, which results in the increase of anharmonicity of polarization vibration and infrared emissivities. The moderate increase of calcining temperature benefits the formation of Ti4+-substituted α-cordierite structure and improvement of infrared radiation properties. The Ti2+-substituted cordierite calcined at 1420°C shows a relalively high emissivity of 0.89 in the whole band and emissivities of 0.90-0.94 in the bands within 8-14 μm.